Hannes Rotzinger

Anisotropic rare-earth spin ensemble strongly coupled to a superconducting resonator.

Interfacing photonic and solid-state qubits within a hybrid quantum architecture offers a promising route towards large scale distributed quantum computing. Ideal candidates for coherent qubit interconversion are optically active spins, magnetically coupled to a superconducting resonator. We report on an on-chip cavity QED experiment with magnetically anisotropic Er(3+)∶Y2SiO5 crystals and demonstrate collective strong coupling of rare-earth spins to a lumped element resonator. Moreover, the electron spin resonance and relaxation dynamics of the erbium spins are detected via direct microwave absorption, without the aid of a cavity.

Ultralow-power spectroscopy of a rare-earth spin ensemble using a superconducting resonator

P. Bushev, A. K. Feofanov, H. Rotzinger, I. Protopopov, J. H. Cole, 4 C. M. Wilson, G. Fischer, A. Lukashenko, and A. V. Ustinov 6 Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany Institut für Nanotechnologie, Karlsruhe Institute of Technology, D-76021 Karlsruhe, Germany Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany Applied Physics, School of Applied Sciences, RMIT University, Melbourne 3001, Australia Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden DFG-Center for Functional Nanostructures (CFN), D-76128 Karlsruhe, Germany (Dated: January 12, 2013)

Three-dimensional cavity quantum electrodynamics with a rare-earth spin ensemble

We present cavity QED experiments with an Er:YSO crystal magnetically coupled to a 3D cylindrical sapphire loaded copper resonator. Such waveguide cavities are promising for the realization of a superconducting quantum processor. Here, we demonstrate the coherent integration of a rare-earth spin ensemble with the 3D architecture. The collective coupling strength of the Er

Multiphoton dressing of an anharmonic superconducting many-level quantum circuit

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Microwave multimode memory with an erbium spin ensemble

spins to the 3D cavity is 21 MHz. The cylindrical sapphire loaded resonator allowed us to explore the anisotropic collective coupling between the rare-earth doped crystal and the cavity. This work shows the potential of spin doped solids in 3D quantum circuits for application as microwave quantum memories as well as for prospective microwave to optical interfaces.

Concentric transmon qubit featuring fast tunability and an anisotropic magnetic dipole moment

We report on the investigation of a superconducting anharmonic multilevel circuit that is coupled to a harmonic readout resonator. We observe multiphoton transitions via virtual energy levels of our system up to the fifth excited state. The back-action of these higher-order excitations on our readout device is analyzed quantitatively and demonstrated to be in accordance with theoretical expectation. By applying a strong microwave drive we achieve multiphoton dressing within our anharmonic circuit which is dynamically coupled by a weak probe tone. The emerging higher-order Rabi sidebands and associated Autler-Townes splittings involving up to five levels of the investigated anharmonic circuit are observed. Experimental results are in good agreement with master-equation simulations.

Superconductor-insulator transition in nanowires and nanowire arrays

Interfacing photonic and solid-state qubits within a hybrid quantum architecture offers a promising route towards large scale distributed quantum computing. In that respect, hybrid quantum systems combining circuit QED with ions doped into solids are an attractive platform. There, the ions serve as coherent memory elements and reversible conversion elements of microwave to optical qubits. Among many possible spin-doped solids, erbium ions offer the unique opportunity of a coherent conversion of microwave photons into the telecom C-band at

Strong coupling of anEr3+-dopedYAlO3crystal to a superconducting resonator

1.54\,\mu

Hybrid quantum circuit with implanted erbium ions

m employed for long distance communication. In our work, we perform a time-resolved electron spin resonance study of an Er

Aluminium-oxide wires for superconducting high kinetic inductance circuits

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